Prosthetic devices which are used to replace missing limbs are typically mounted by a socket to the residual limb or amputation stump of a patient. The sockets are most preferably custom made to conform to the configuration of the residual limb so as to be capable of supporting weight, in the case of a leg, or loading forces, in the case of an arm.
It has been found that it is highly desirable for patients to begin use of prosthetic devices as soon as possible after the required or accidental amputation of a limb. If a patient can be fitted with a prosthetic device soon after limb amputation, the prognosis for long term, effective use of the prosthetic is much higher. Additionally, the adverse psychological impact of an amputation can most effectively be minimized by rapid adaptation of the patient to a prosthetic in order to reinforce the patient's realization that he or she will be able to be self-sufficient.
While it is generally accepted that it is desirable to have patients begin using prosthetic devices soon after a limb amputation, there are serious practical difficulties in implementing such a procedure. Immediately after limb amputation, whether such amputation was a result of a planned surgical protocol or traumatic accidental occurrence, the residual limb or amputation stump will experience considerable post-operative or post-trauma edema or swelling. Such edema, of course, is also accompanied with considerable pain and discomfort. Even after the pain and discomfort subside to acceptable levels, the edema will continue for two to three months until the body gradually absorbs the fluids from the residual limb.
Since limb prosthetic devices are most typically mounted to a patient by a socket which is customized to the configuration of the patient's residual limb, formation of a prosthetic socket within a few weeks of limb amputation results in a socket which conforms to the configuration of the swollen or edema-affected residual limb.
One approach to forming prosthetic sockets, for example, is to form a plaster of Paris or other cast of the residual limb. The cast is removed from the limb and used in the laboratory as a negative. A positive plaster of Paris cast can be made from the negative and then a residual limb prosthetic socket built in the laboratory over the positive. Typical of prior art using this general approach are the systems described in U.S. Pat. Nos. 1,351,789; 1,907,511; 4,307,056; 4,473,421; 5,376,127; 5,376,129; 5,376,132; 5,405,405; and 5,503,543. These patents describe techniques of using a negative cast made from the residual limb as a basis for creating a customized prosthetic socket. Common to these various systems is the labor-intensive reality of making negatives, positives and thereafter forming a prosthetic socket on the positive. Accordingly, prosthetic sockets formed using such conventional techniques have been relatively expensive.
More recently, prosthetic systems have been devised which eliminate the need for formation of a negative of the residual limb. Rather than taking the negative to a laboratory, forming a positive and thereafter forming the socket, these techniques employ casting the socket in place directly on the patient's residual limb. Prior art showing this type of system includes U.S. Pat. Nos. 4,193,395; 4,923,474; 5,258,036; and 5,387,245.
One cast-in-place system is now commercially available in the United States under the ICEX trademark through Ossur USA, Inc. of Carpeteria, Calif. The Ossur USA system is described in detail in a manual entitled "IceCast Compact Technical Manual." Even such in-situ or cast-in-place systems, however, are very expensive.
The materials in the Ossur USA ICEX system, for example, will cost over $600, primarily because a carbon fiber sock is used to make a permanent (3 to 5 years) prosthetic socket.
The major problem which has occurred in prior art prosthetic socket casting procedures has been that, if the procedure is performed early, the resulting socket will reflect the edema or swelling in the residual limb. As the patient's body absorbs the edema, however, the swelling will subside, resulting in a poor fit between the prosthetic socket and the residual limb. Patients attempt to accommodate this edema absorption by adding additional socks over their residual limb before placing the limb in the prosthetic socket. The additional socks are used to fill the space left in the socket as a result of limb shrinking due to edema absorption. Since the edema will not generally be uniform and socks are uniform, the use of this technique is only partially satisfactory.
Two other approaches are taken to accommodate residual limb shrinkage. The first is to simply recast the socket, that is, to form a second prosthetic socket after the edema has dissipated, for example in two to three months. The second is to wait two to three months before forming the prosthetic socket. Both of these approaches have substantial disadvantages. The first is costly, while the second is undesirable in terms of the likelihood of the patient's successful adaptation to the prosthetic and psychological problems attendant to waiting.
Accordingly, it is an object of the present invention to provide a method for forming prosthetic sockets for patients' residual limbs which can be used during the post-operative or post-trauma period in which the patient's residual limb is swollen with edema.
Another object of the present invention is to provide a method and a temporary prosthetic socket which provides better conformance to the patient's residual limb.
Still a further object of the present invention is to provide a method and apparatus for forming prosthetic sockets which is relatively low in cost, minimizes pain and discomfort to the patient, and can be used with patients which have very substantial residual limb swelling.
The present invention has other objects and features of advantage which will become apparent from, or are set forth in more detail in, the accompanying drawings and the following Best Mode of Carrying Out the Invention.